Rotary electrical switch with bridging contactor

ABSTRACT

A rotary electrical switch has a stator block carrying a number of groups of contacts arranged in a circular array. A rotor is rotatable between two positions about the axis of the contact array and carries a plurality of contactors or wipers each bridging one pair of contacts in one position of the rotor and another pair of contacts in a second position of the rotor. The contactors are mounted on the stator block with looseness in two degrees of freedom of movement to allow them to move toward and away from the contact array and about radial axes perpendicular to the axis of rotor rotation; and, a spring urges each contactor toward the contact array with the spring force being applied to the contactor at a point which is located between the two contacts bridged by the contactor when the rotor is in either its first or second position, whereby the contactor is pressed against each of the two bridged contacts by substantially equal forces.

United States Patent 1191 Terry, deceased et al.

14 1 Dec. 24, 1974 ROTARY ELECTRICAL SWITCH WITH BRIDGING CONTACTOR [73] Assignee: Maremont Corporation, Saco, Mass.

[22] Filed: Jan. 3, 1974 [21] Appl. No.: 430,533

[52] US. Cl 200/11 K, 200/164, ZOO/260,

200/290 [51] Int. Cl ..H01h 19/58, HOlh l/48 [58] Field of Search 200/11, 252, 260, 261,

zoo/273, 274, 286, 287, 290, 11 EA, 11 J, 200/11 K, 257, 259, 164

[56] References Cited UNITED STATES PATENTS 2,064,157 12/1936 Franklin 200/11 D 3,098,130 7/1963 Clavel ..200/11K 3,198,895 8/1965 200/11 R X 3,226,495 12/1965 ..200/11K 3,267,224 8/1966 Vega 200/ll EA 2O P-q 1 10 1-' i 16 I I8 I 1 l 41 24 3,363,068 l/l968 Schwab ZOO/ll D Primary Examiner-James R. Scott Attorney, Agent, or FirmMcCormick, Paulding &

Huber [57] ABSTRACT A rotary electrical switch has a stator block carrying a number of groups of contacts arranged in a circular array. A rotor is rotatable between two positions about the axis of the contact array and carries a plurality of contactors or wipers each bridging one pair of contacts in one position of the rotor and another pair of contacts in a second position of the rotor. The contactors are mounted on the stator block with looseness in two degrees of freedom of movement to allow them to move toward and away from the contact array and about radial axes perpendicular to the axis of rotor rotation; and, a spring urges each contactor toward the contact array with the spring force being applied to the contactor at a point which is located between the two contacts bridged by the contactor when the rotor is in either its first or second position, whereby the contactor is pressed against each of the two bridged contacts by substantially equal forces.

4 Claims, 8 Drawing Figures PATENTED DEB24|974 SHEET 2 BF 2 ROTARY ELECTRICAL SWITCH WITH BRIDGING CONTACTOR BACKGROUND OF THE INVENTION This invention relates to rotary electrical switches, and more particularly deals with such a switch having a stator block carrying a number of contacts and a rotor block carrying at least one contactor for bridging different ones of said contacts in different positions of said rotor to establish electrical connection between the bridged contacts.

The switch of this invention may be put to many different uses and is particularly suited to applications where it is necessary to concurrently switch a number of circuits carrying relatively high levels of current. One example of such a use is one involving the switching of the generating windings of a three-phase electric generator, such as shown in copending US. Pat. application Ser. No. 327,207, used alternatively as a source of power for electric welding and as an auxiliary power unit, between a delta configuration and a wye configuration. This switching of the generating windings from one configuration to the other requires the concurrent switching of three different circuits, and, preferably, the switch used for this purpose also has the capacity of interrupting the circuit to the field winding of the generator so that during the transition between configurations, the field winding is de-energized to allow the transition to be made while little or no current is flowing through the generating windings.

Typically, generators of the type disclosed in the aforesaid copending application are designed to deliver rated output current in the order of 100 amps to 200 amps or more. In the past, switches capable of concurrently switching a number of circuits of the current capacity involved in such an application have tended to be quite large, expensive, of complex construction and often difficult to operate. The purpose of this invention, therefore, is to provide an electrical switch of easily operated rotary construction capable of concurrently switching a number of high current circuits and which switch is of a compact size and of a relatively inexpensive, yet reliable, simple construction.

Another object of the invention is to provide in a rotary electrical switch having a bridging contactor or wiper carried by a rotor and movable by the rotor into bridging relation with different sets of contacts carried by a stator, a construction of the contactor and its mounting means for assuring a uniform pressure between the contactor and the contacts bridged thereby despite possible differences in the heights of the contacts from a reference plane perpendicular to the axis of rotor rotation.

SUMMARY OF THE INVENTION The invention resides in a rotary electrical switch having a stator block carrying a circular array of angularly spaced contacts. Located within the circular contact array is a rotor block rotatable about the axis of the array and carrying a number of contactors or wipers extending radially outwardly from the rotor block and having flat contact faces extending circumferentially of the contact array for a distance sufficient to simultaneously bridge two adjacent contacts. Preferably, each contactor cooperates with an associated group of three contacts and, by rotation of the rotor between first and second limit positions, it is moved from aposition at which it bridges the center one of the three contacts and one of the other two contacts to a position at which it bridges the center contact and the other of the two contacts. In a specific form of this aspect of the invention, the switch includes four contactors each cooperating with an exclusively associated group of three contacts. All of the contactors are of such a circumferential length as to function in a break-before-make manner in moving from bridging relationship with one pair of contacts to bridging relationship with the other pair of contacts. One of the contactors, however, is of a shorter circumferential length than the other contactors so that the connections made by it break in advance of the connections made by the other contactors as the rotor is shifted from one of its positions to its other position.

The invention also resides in a novel construction and mounting for the contactors of a rotary electrical switch whereby the contactors are loosely mounted, in certain degrees of freedom of movement, to a rotor block and spring biased against the associated contacts of a stator block by a spring means which engages each contactor at a point located between the two bridged contacts to cause substantially equal forces to be exerted by the contactor against each of the two bridged contacts.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a rear elevational view of a rotary electrical switch embodying this invention with the rotor thereof being shown in one of its two limited positions.

FIG. 2 is a sectional view taken on the line 2-2 of FIG. 1.

FIG. 3 is a fragmentary view similar to FIG. 1 but showing the rotor in the other of its two limited positions.

FIG. 4 is a rear elevational view of the stator assem* bly used in the switch of FIG. 1.

FIG. 5 is a front elevational view of the stator assembly of FIG. 4.

FIG. 6 is a front elevational view of the rotor assembly used in the switch of FIG. 1.

FIG. 7 is an exploded view showing the manner in which one of the contactors of the rotor assembly of FIG. 6 is mounted to the rotor block.

FIG. 8 is a fragmentary sectional view taken on the line 88 of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Turning to the drawings, and first considering FIGS. 1 and 2, a rotary electrical switch is illustrated and comprises basically a stator assembly or stator 10 and a rotor assembly or rotor 12. The stator 10 is made of a generally disc-shaped block of electrically nonconductive material 14 having on its rear face a circular array of twelve contacts 16, 16. As shown best in FIG. 2, each contact 16 is part of a rivet 18 having a shank passing through an associated terminal 20 and the stator block 14. The right-hand end of each contact rivet 18, as viewedin FIG. 2, is peened over a washer 22 to fix the rivet and the terminal 22 to the stator block.

As evident from FIGS. 2 and 5, the stator block 14 has a recess 24 at the location of each rivet 18 to space the washer 22 and peened end of the rivet from any mounting panel to which the stator block may be attached in use. In FIG. 2, such a mounting panel is shown in broken line form and indicated by the reference numeral 26. As shown best in FIGS. 4 and 5, a number of holes 28, 28 pass through the stator block 14 to accommodate fasteners for holding the stator to a panel, such as the one indicated at 26 in FIG. 2, and such openings 28, 28 are counterbored adjacent the rear face of the stator block, seen in FIG. 4, to receive the heads or nuts of the fasteners.

To accommodate the rotor 12, the stator block 14 includes a circular recess 30 in its rear face and a central circular opening 32, the recess 30 and opening 32 both being concentric with the circular array of contacts. In the base of the circular recess 30 is a further arcuate recess 34, FIG. 4, having two generally radially extending end walls 36, 36.

The rotor 12 includes a circular rotor block 38, a central shaft 40 and four contactors or wipers 40, 41, 42 and 43. On the inner face of the rotor block 38 is a stop lug 44. In the assembled switch, as seen in FIGS. 1 and 2, the rotor block 38 is received in the circular recess 30 and the shaft 40 passes through the central opening 32 of the stator block to rotatably support the rotor block for rotation relative to the stator block about the axis of the opening 32. The shaft 40 is fixed to the rotor block 38 by a roll pin 46 passing through the shaft and received in a slot in the rotor block, and the shaft is limited in axial movement to the left, as viewed in FIG. 2, relative to the stator block by a washer 48 and roll pin 50. The right-hand end of the shaft is provided with a flat 52 for cooperation with a set screw used to attach a knob 54 thereto.

Referring again to FIG. 1, each of the four contactors 41 to 43 is associated with a respective one of four groups of three contacts 16, 16. In this figure, the three terminals 20, 20 connected to the three contacts 16, 16 associated with the contactor 43 are each marked by the reference character a. Likewise, the reference characters b indicate the terminals and contacts associated with the contactor 42, the reference characters c indicate the terminals and contacts associated with the contactor 41 and the reference characters d indicate the terminals and contacts associated with the contactor 40. In the vicinity of the circular contact array, each contactor is of such a length as to be capable of bridg ing two of its associated contacts 16, 16.

The stop lug 44 on the rotor block is received in the arcuate recess 34 of the stator block and acts to restrict movement of the rotor relative to the stator to movement between two limit positions shown respectively in FIGS. 1 and 3. In particular, the contacts of the illustrated switch are equally angularly spaced from one another by 30, and the shape and size of the stop lug 44 and recess 34 are such that movement of the rotor relative to the stator is limited to a corresponding displacement of 30. From a comparison of FIGS. 1 and 3, it will be noted that in one of the limit positions of the rotor, the contactor 43 bridges one pair of contacts consisting of the middle contact and the left contact of the associated group of contacts, and in the other limit position, it bridges another pair of contacts consisting of the middle contact and the right contact of the associated group of contacts. The middle contact of the group is, therefore, a common contact and as the rotor is shifted from one limit position to the other, this middle or common contact is switched from electrical connection with one of the other two contacts to electrical connection with the other of the other two contacts. The operation of the other three contactors 40, 41 and 42 is the same as that for the contactor 43. Therefore, as the rotor is rotated between its two limit positions, external circuits connected with and controlled by the four groups of contacts are all simultaneously switched.

In the illustrated switch, the four contactors 40 to 43 are all of such arcuate length that as the rotor is shifted from one position to the other, the contact wiping face of the contactor will not at any point in the movement of the rotor simultaneously bridge all three of its contacts. That is, in the middle portion of the rotor movement, the contactor will engage only the middle one of its associated three contacts, thereby yielding a break-before-make type of switching action. Also, in the illustrated switch, the contactors 41, 42 and 43 are all of a uniform length in the vicinity of the circular contact array so that the breaking and making of the circuits controlled by these contactors occur at virtually the same instant during rotor rotation. The contactor 40, however, is of a slightly smaller length than the contactors 41, 42 and 43. Accordingly, as the rotor is moved from one limit position, the contactor 40 first breaks its original electrical connection slightly ahead of the breaking of the original connections made by the other three contactors, then the contactor 40 makes its new connection slightly later than the new connections are made by the other three contactors. This is of advantage in use of the switch, for example, in the afore* mentioned application of switching the generating windings of a wound field three-phase generator between delta and wye configurations. In such applica tion, the contacts associated with the three contactors 41, 42 and 43 are connected with the generating windings and the terminals associated with the contactor 40 are used to control the energization of the generator field winding. Accordingly, as the rotor of the switch is shifted from one limit position to the other, the field winding is de-energized ahead of and during the tine of the switching of the generating windings so that the change in winding configuration occurs under a noload condition.

Of course, it will be obvious that although the illustrated swtitch shows the contactors as being of such a length as to provide a break-before-make action for each of the four groups of contacts, any one or more of the contactors could be made of increased length sufficient to provide a make-before-break type of action. Also, the contacts may be of varying different lengths to obtain different sequences in the timing of the breaking and making of the electrical connections between the contacts of the various groups. Also, similar modifications may be had by varying the angular spacing between the contacts of each group while maintaining the circumferential length of the contactors uniform.

The contactors are mounted to the rotor block 38 in such a manner as to achieve substantially equal forces between the contactor and each of the two contacts bridged thereby in both of the two limit positions of the rotor despite possible differences in the heighth of the contact faces from a reference plane perpendicular to the axis of rotor rotation. Referring to FIGS. 1, 2, 6 and 7, each contactor is of a general T-shape and has a circumferentially extending wiping portion 56 and a radially extending leg 58, the wiping portion 56 having a generally flat contact engaging face 60 and being turned up at each of its ends 62, 62. The leg 58 of each contactor is received in a radially extending recess 64 of the rotor block 38 and has an opening 66 through which passes the shank of a rivet 68. As shown best in FIG. 8, the leg 58 fits relatively closely between the radially extending side walls of the recess 74 so that the contactor is constrained to move angularly with the rotor block 38 about the axis of the shaft 39. However, the opening 66 in the contactor is substantially larger than the diameter of the shank of the rivet 68 so that the contactor has a certain amount of looseness in two different degrees of freedom of movement. That is, the outer end or wiping portion 56 of the contactor is movable slightly toward and away from associated contacts l6, l6 and also the contactor is rotatable to a slight degree about an axis, shown at 69 in FIG. 7 perpendicular to the central axis of the rotor.

Outboard of each contactor is a spring member 70 through which the rivet 68 passes. The rivet also passes through a washer 72 and is peened at its end adjacent the rivet to hold it, the rotor block, the associated contactor and the spring member in assembly with one another. At its inner end, the spring member is wider than the recess 64 so as to rest on the adjacent face of the stator block. At its outer end, the spring member is of a narrower dimension and is shaped to engage the associated contactor at a point substantially midway between its ends 62, 62. The shape and dimension of the spring members and other parts of the switch are such that when the switch is assembled, as shown for example in FIG. 2, the spring members 70, 70 are held in a deflected state so that they exert spring forces on the associated contactors to urge the faces of such contactors against the adjacent contacts l6, 16. At either limit position of the rotor, each spring member engages its contactor at a location approximately midway between the two bridged contacts and because of this and the looseness in the connection of the contactor to the rotor block, the face of the contactor is forced against each contact with substantially equal force.

What is claimed is:

1. An electrical switch for concurrently switching a plurality of circuits, said switch comprising a stator block of electrically non-conductive material, a rotor block of electrically non-conductive material, means supporting said rotor block for rotation relative to said stator block about a first axis fixed relative to both of said blocks, stop means for limiting said rotation of said rotor block to rotation between first and second positions of said rotor block relative to said stator block, a plurality of groups of contacts on said stator block each of which groups of contacts includes a plurality of individual contacts angularly spaced from one another about said first axis and located in a plane generally perpendicular to said first axis, a plurality of contactors carried by said rotor block and each associated with a respective one of said groups of stator contacts, each of said contactors having a generally flat face located in a plane generally perpendicular to said first axis and arranged to wipe over its associated group of said stator contacts when said rotor block is rotated relative to said stator block, connecting means connecting each of said contactors to said rotor block and constraining said contactor to rotate with said rotor block about said first axis as said rotor block is rotated between said first and second positions, said connecting means including means providing a limited amount of looseness between said contactor and said rotor block in two degrees of freedom of movement, one of said two degrees of freedom involving movement of said face of said contactor toward and away from said plane of its associated stator contacts and the other of said two degrees of freedom involving rotation of said face of said contactor about a radial axis generally perpendicular to said first axis, said generally fiat face of each contactor being of such length arcuately about said first axis as to contact and bridge two of said stator contacts when said rotor block is in said first position, and the angular displacement of said rotor block permitted by said stop means being such that as said rotor block is moved from said first position to said second position and said generally flat face of each contactor is moved out of contact with at least one of the two of said contacts contacted by said flat face in said first position of said rotor block, and a spring means for applying to each of said contactors a force urging the face of such contactor toward and against its associated contacts, said force being applied to such contactor at a point thereon which is located angularly between the two contcts bridged by said contactor when said rotor block is in said first position.

2. An electrical switch for concurrently switching a plurality of circuits, said switch comprising a stator block of electrically non-conductive material, a rotor block of electrically non-conductive material, means supporting said rotor block for rotation relative to said stator block about a first axis fixed relative to both of said blocks, a plurality of contacts on said stator block angularly spaced from one another about said first axis and located in a plane generally perpendicular to said first axis, a contactor carried by said rotor block and having a generally flat face located in a plane generally perpendicular to said first axis and arranged to wipe over said contacts when said rotor block is rotated relative to said stator block, connecting means connecting said contactor to said rotor block and constraining said contactor to rotate with said rotor block about said first axis as said rotor block is rotated relative to said stator block, said connecting means including means providing a limited amount of looseness between said contactor and said rotor block in two degrees of freedom of movement, one of said two degrees of freedom involving movement of said face of said contactor toward and away from said plane of said contacts and the other of said two degrees of freedom involving rotation of said face of said contactor about a radial axis generally perpendicular to said first axis, said generally flat face of said contactor being of such length arcuately about said first axis as to contact and bridge only two adjacent ones of said contacts when said rotor is in a given position relative to said stator block, and a spring means for applying to said contactor a force urging the face of said contactor toward said plane of said contacts, said force being applied to said contactor at a point thereon which is located angularly between the two contacts bridged by said contactor when said rotor block is in said given position.

3. An electrical switch as defined in claim 2 further characterized by said generally flat face of said contactor being located radially outwardly of said rotor block and said contactor having a radially extending leg between said generally flat face thereof and said rotor block, said connecting means including a generally rasaid inner end portion of said contactor leg, said latter opening being of a larger diameter than said fastener so as to loosely hold said contactor to said rotor block.

4. An electrical switch as defined in claim 3 further characterized by said spring means comprising a spring member fixed to said rotor block by said fastener. 

1. An electrical switch for concurrently switching a plurality of circuits, said switch comprising a stator block of electrically non-conductive material, a rotor block of electrically non-conductive material, means supporting said rotor block for rotation relative to said stator block about a first axis fixed relative to both of said blocks, stop means for limiting said rotation of said rotor block to rotation between first and second positions of said rotor block relative to said stator block, a plurality of groups of contacts on said stator block each of which groups of contacts includes a plurality of individual contacts angularly spaced from one another about said first axis and located in a plane generally perpendicular to said first axis, a plurality of contactors carried by said rotor block and each associated with a respective one of said groups of stator contacts, each of said contactors having a generally flat face located in a plane generally perpendicular to said first axis and arranged to wipe over its associated group of said stator contacts when said rotor block is rotated relative to said stator block, connecting means connecting each of said contactors to said rotor block and constraining said contactor to rotate with said rotor block about said first axis as said rotor block is rotated between said first and second positions, said connecting means including means providing a limited amount of looseness between said contactor and said rotor block in two degrees of freedom of movement, one of said two degrees of freedom involving movement of said face of said contactor toward and away from said plane of its associated stator contacts and the other of said two degrees of freedom involving rotation of said face of said contactor about a radial axis generally perpendicular to said first axis, said generally flat face of each contactor being of such length arcuately about said first axis as to contact and bridge two of said stator contacts when said rotor block is in said first position, and the angular displacement of said rotor block permitted by said stop means being such that as said rotor block is moved from said first position to said second position and said generally flat face of each contactor is moved out of contact with at least one of the two of said contacts contacted by said flat face in said first position of said rotor block, and a spring means for applyinG to each of said contactors a force urging the face of such contactor toward and against its associated contacts, said force being applied to such contactor at a point thereon which is located angularly between the two contcts bridged by said contactor when said rotor block is in said first position.
 2. An electrical switch for concurrently switching a plurality of circuits, said switch comprising a stator block of electrically non-conductive material, a rotor block of electrically non-conductive material, means supporting said rotor block for rotation relative to said stator block about a first axis fixed relative to both of said blocks, a plurality of contacts on said stator block angularly spaced from one another about said first axis and located in a plane generally perpendicular to said first axis, a contactor carried by said rotor block and having a generally flat face located in a plane generally perpendicular to said first axis and arranged to wipe over said contacts when said rotor block is rotated relative to said stator block, connecting means connecting said contactor to said rotor block and constraining said contactor to rotate with said rotor block about said first axis as said rotor block is rotated relative to said stator block, said connecting means including means providing a limited amount of looseness between said contactor and said rotor block in two degrees of freedom of movement, one of said two degrees of freedom involving movement of said face of said contactor toward and away from said plane of said contacts and the other of said two degrees of freedom involving rotation of said face of said contactor about a radial axis generally perpendicular to said first axis, said generally flat face of said contactor being of such length arcuately about said first axis as to contact and bridge only two adjacent ones of said contacts when said rotor is in a given position relative to said stator block, and a spring means for applying to said contactor a force urging the face of said contactor toward said plane of said contacts, said force being applied to said contactor at a point thereon which is located angularly between the two contacts bridged by said contactor when said rotor block is in said given position.
 3. An electrical switch as defined in claim 2 further characterized by said generally flat face of said contactor being located radially outwardly of said rotor block and said contactor having a radially extending leg between said generally flat face thereof and said rotor block, said connecting means including a generally radially extending recess in said rotor block receiving the radially inner end portion of said contactor leg and having side walls closely adjacent to the side edges of said contactor leg to constrain said contactor to movement with said rotor block about said first axis, and a fastener fixed to said rotor block, said fastener extending parallel to said first axis and passing through an opening in said inner end portion of said contactor leg, said latter opening being of a larger diameter than said fastener so as to loosely hold said contactor to said rotor block.
 4. An electrical switch as defined in claim 3 further characterized by said spring means comprising a spring member fixed to said rotor block by said fastener. 